Bifurcated contact printing technique

ABSTRACT

A method for spreading a conformable material between a substrate and a template having a mold. The method comprises positioning the mold to be in superimposition with the substrate defining a volume therebetween. A first sub-portion of the volume is charged with the conformable material through capillary action between the conformable material and one of the mold and the substrate. A second sub-portion of the volume is filled with the conformable material by creating a deformation in the mold.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

The present application is a divisional patent application of U.S.patent application Ser. No. 11/292,568, filed Dec. 1, 2005 and entitled“Technique for Separating a Mold from Solidified Imprinting Material,”and listing Mahadevan GanapathiSubramanian, Byung-Jin Choi, Michael N.Miller, and Nicholas A. Stacey as inventors, the entirety of which isincorporated by reference herein.

BACKGROUND OF THE INVENTION

The field of invention relates generally to nano-fabrication ofstructures. More particularly, the present invention is directed to amethod for improving contact imprinting employed in imprint lithographicprocesses.

Nano-scale fabrication involves the fabrication of very smallstructures, e.g., having features on the order of one nanometer or more.A promising process for use in nano-scale fabrication is known asimprint lithography. Exemplary imprint lithography processes aredescribed in detail in numerous publications, such as United Statespublished patent application 2004/0065976 filed as U.S. patentapplication Ser. No. 10/264,960, entitled “Method and a Mold to ArrangeFeatures on a Substrate to Replicate Features having Minimal DimensionalVariability”; United States published patent application 2004-0065252filed as U.S. patent application Ser. No. 10/264,926, entitled “Methodof Forming a Layer on a Substrate to Facilitate Fabrication of MetrologyStandards”; and U.S. Pat. No. 6,936,194, entitled “Method and a Mold toArrange Features on a Substrate to Replicate Features having MinimalDimensions Variability”; all of which are assigned to the assignee ofthe present invention.

Referring to FIG. 1, the basic concept behind imprint lithography isforming a relief pattern on a substrate that may function as, interalia, an etching mask so that a pattern may be formed into the substratethat corresponds to the relief pattern. A system 10 employed to form therelief pattern includes a stage 11 upon which a substrate 12 issupported, and a template 14 having a mold 16 with a patterning surface18 thereon. Patterning surface 18 may be substantially smooth and/orplanar, or may be patterned so that one or more recesses are formedtherein. Template 14 is coupled to an imprint head 20 to facilitatemovement of template 14. A fluid dispense system 22 is coupled to beselectively placed in fluid communication with substrate 12 so as todeposit polymerizable material 24 thereon. A source 26 of energy 28 iscoupled to direct energy 28 along a path 30. Imprint head 20 and stage11 are configured to arrange mold 16 and substrate 12, respectively, tobe in superimposition, and disposed in path 30. Either imprint head 20,stage 11, or both vary a distance between mold 16 and substrate 12 todefine a desired volume therebetween that is filled by polymerizablematerial 24. The relative positions of substrate 12 and stage 11 ismaintained employing standard chucking techniques. For example, stage 11may include a vacuum chuck, such as a pin chuck (not shown) coupled to avacuum supply (not shown).

Typically, polymerizable material 24 is disposed upon substrate 12before the desired volume is defined between mold 16 and substrate 12.However, polymerizable material 24 may fill the volume after the desiredvolume has been obtained. After the desired volume is filled withpolymerizable material 24, source 26 produces energy 28, which causespolymerizable material 24 to solidify and/or cross-link, formingpolymeric material conforming to the shape of the substrate surface 25and mold surface 18. Control of this process is regulated by processor32 that is in data communication with stage 11 imprint head 20, fluiddispense system 22, and source 26, operating on a computer-readableprogram stored in memory 34.

An important characteristic with accurately forming the pattern inpolymerizable material 24 is to ensure that the dimensions of thefeatures formed in the polymerizable material 24 are controlled.Otherwise, distortions in the features etched into the underlyingsubstrate may result.

A need exists, therefore, to improve the imprinting technique employedin contact lithographic processes.

SUMMARY OF THE INVENTION

The present invention provides a method for spreading a conformablematerial between a substrate and a template having a mold. The methodcomprises positioning the mold to be in superimposition with thesubstrate defining a volume therebetween. A first sub-portion of thevolume is charged with the conformable material through capillary actionbetween the conformable material and one of the mold and the substrate.A second sub-portion of the volume is filled with the conformablematerial by creating a deformation in the mold. These and otherembodiments are described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified plan view of a lithographic system in accordancewith the prior art;

FIG. 2 is a simplified plan view of a template and imprinting materialdisposed on a substrate in accordance with the present invention;

FIG. 3 is a simplified plan view of the template and substrate, shown inFIG. 2, with the imprinting material being shown as patterned andsolidified upon the substrate;

FIG. 4 is a detailed view of the substrate shown in FIGS. 2 and 3, inaccordance with the present invention;

FIG. 5 is a detailed view of the substrate shown in FIG. 4 having asolidified formation of imprinting material disposed thereon;

FIG. 6 is a detailed view of the substrate shown in FIG. 5 after beingsubjected to an etching chemistry to expose regions of the substrate;

FIG. 7 is a detailed view of the substrate shown in FIG. 6 after beingsubjected to an etch and removal of the solidified imprinting material;

FIG. 8 is a cross-sectional view of a flexible template in accordancewith the present invention;

FIG. 9 is a cross-sectional view of the mold shown in FIG. 8 imprintingpolymerizable material disposed on the substrate shown in FIG. 4, inaccordance with the present invention;

FIG. 10 is a detailed view of the mold shown in FIG. 9 before the samehas conformed to a shape of the substrate;

FIG. 11 is a detailed view of the substrate shown in FIG. 9 after beingsubjected to an etching chemistry to expose regions of the substrate;

FIG. 12 is a detailed view of the substrate shown in FIG. 9 after beingsubjected to an etch and removal of the solidified imprinting material;

FIG. 13 is a cross-sectional view of the flexible template shown in FIG.8, in accordance with an alternate embodiment of the present invention;

FIG. 14 is a cross-sectional view of the flexible template shown in FIG.8, in accordance with a second alternate embodiment of the presentinvention;

FIG. 15 is a cross-sectional view of the flexible template shown in FIG.8, in accordance with a third alternate embodiment of the presentinvention;

FIG. 16 is a flow diagram showing an exemplary imprinting operationemploying the template shown in FIG. 12, in accordance with the presentinvention;

FIG. 17 is a simplified plan view of a chucking system employed toretain the template shown in FIG. 13, with the template being disposedproximate to a substrate;

FIG. 18 is a bottom up view of a chuck body shown in FIG. 17;

FIG. 19 is an exploded perspective view of components included in animprint head, shown in FIG. 1 in accordance with the present invention;

FIG. 20 is a bottom perspective view of the components shown in FIG. 19;

FIG. 21 is a simplified plan view of the chucking system shown in FIG.17 with the template undergoing deformation to facilitate separation ofthe template from solidified imprinting material present on thesubstrate;

FIG. 22 is a detailed view of region 217, shown in FIG. 21, inaccordance with an alternate embodiment;

FIG. 23 is a simple plan view of template 214 shown in FIG. 21;

FIG. 24 is a detailed cross-section view showing the template of FIG. 21undergoing separation from formation 50; and

FIG. 25 is a simplified cross-sectional view of the template shown inFIG. 21.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 and 2, a mold 36, in accordance with the presentinvention, may be employed in system 10, and may define a surface havinga substantially smooth or planar profile (not shown). Alternatively,mold 36 may include features defined by a plurality of spaced-apartrecessions 38 and protrusions 40. The plurality of features defines anoriginal pattern that is to be transferred into a substrate 42.Substrate 42 may be comprised of a bare wafer or a wafer with one ormore layers disposed thereon. To that end, reduced is a distance “d”between mold 36 and substrate 42. In this manner, the features on mold36 may be imprinted into an imprinting material, such as polymerizablematerial 24, disposed on a portion of surface 44 that presents asubstantially planar profile. It should be understood that substrate 42may be a bare silicon wafer 48 or may include a native oxide or one ormore layers, shown as primer layer 45. In the present example, substrate42 is discussed with respect to including a primer layer 45. Exemplarycompositions from which primer layer 45 and polymerizable material 42may be formed are discussed in U.S. patent application Ser. No.11/187,406, filed Jul. 22, 2005, entitled COMPOSITION FOR ADHERINGMATERIALS TOGETHER, having Frank Xu listed as the inventor, assigned tothe assignee of the present invention and is incorporated by referenceherein.

Referring to both FIGS. 2 and 3, the imprinting material may bedeposited using any known technique, e.g., spin-coating, dip coating andthe like. In the present example, however, the imprinting material isdeposited as a plurality of spaced-apart discrete droplets 46 onsubstrate 42. Imprinting material is formed from a composition that maybe selectively polymerized and cross-linked to record the originalpattern therein, defining a recorded pattern.

Specifically, the pattern recorded in the imprinting material isproduced, in part, by interaction with mold 36, e.g., electricalinteraction, magnetic interaction, thermal interaction, mechanicalinteraction or the like. In the present example, mold 36 comes intomechanical contact with the imprinting material, spreading droplets 46,so as to generate a contiguous layer of the imprinting material oversurface 44 that is solidified into a formation 50. Formation 50 includesprojections 52 and recessed regions 34. A height thickness t₁ offormation 50 is defined by projections 52. Recessed region 54 defines aresidual thickness t₂ of formation 50. In one embodiment, distance “d”is reduced to allow imprinting material to ingress into and fillrecessions 38. To facilitate filling of recessions 38, before contactbetween mold 36 and droplets 46, the atmosphere between mold 36 anddroplets 46 is saturated with helium or is completely evacuated or is apartially evacuated atmosphere of helium.

Referring to FIGS. 2, 3 and 4, a problem addressed by the presentinvention concerns controlling the thickness of t₁ and t₂ after reachinga desired distance d. Specifically, exemplary dimensions of the featuresof mold 36, e.g., width W₁ of protrusions 40 and width W₂ of recessions38, may be in the range of 30 to 100 nanometers. Height with thicknesst₁ may be in a range of 400 nanometers to one micrometer ±20-80nanometers. Residual thickness t₂ may be in a range of 400 nanometers toone micrometer ±20-80 nanometers. Thus, a height of projections 52,measured from a nadir surface 55, is in a range 40 to 140 nanometers. Asa result, surface 44 presents a non-planar profile, e.g., undulationsare present as hills 56 and troughs 57. The undulations make problematiccontrolling thicknesses t₁ and t₂.

Referring to FIGS. 3, 4 and 5, undulations make difficult ensuring thatthickness t₁ is substantially equal over the area of formation 150 andthickness t₂ is substantially equal over the area of formation 150. Forexample, after solidifying imprinting material, formation 150 is formedin which regions over which thickness t₁ varies and thickness t₂ varies.For example, features in region 58 have a height thickness t′₁±δt′₁ anda residual thickness t′₂±δt′₂, where δt′₁ and δt′₂ results from thevariation in thickness t′₁ and t′₂, respectively, due to the curvatureof surface 44 in superimposition with region 58. Similarly, features inregion 60 have a height thickness t″₁±δt″₁ and a residual thicknesst″₂±δt″₂, where δt″₁ and δt″₂ correspond to the variation in thicknessest″₁ and t″₂, respectively, due to the curvature of surface 44 insuperimposition with region 60.

Referring to FIGS. 5, 6 and 7, were the difference between residualthicknesses t′₂±δt′₂ and t″₂±δt″₂ greater than t′₁±δt′₁, a distortion inthe pattern formed in substrate 42 would occur. This can be seen afterformation 150 has undergone a break-through etch to expose regions 62and 64 and 66 of substrate 42. Were it desired to commence etching ofregions 62, 64 and 66, the result would be recesses 68, 70 and 72, witha largely unpatterned region 74 being present that results from noexposure of substrate 42 during the break-through etch. This isundesirable. Were it desired to pattern region 84 of substrate 42,etching of formation 150 would occur until a break-through in region 60occurs. This would cause substantially all of the features of region 58to be removed. As a result, large regions of substrate 42 would remainunpatterned, due, inter alia, to the absence of masking material.

Referring to FIGS. 3, 4 and 8, to reduce, if not abrogate, the problemspresented by the undulations, template 114, including a mold 136, ismade so as to conform to surface 44. In this manner, mold 136 mayconform in response to the presence of undulations, thereby minimizingvariations among thickness t₁ and variations among thickness t₂ over thearea of formation 50. To that end, template 114 is fabricated from arelatively thin sheet of fused silica having a thickness 113, measuredfrom opposed sides 115 and 116, up to approximately 1.5 millimeters,with of approximately 0.7 being preferred. With a thickness of 0.7millimeter, flexibility is provided by establishing an area of template114 to be approximately 4,225 square millimeters. The area of mold 136may be any desired, e.g., from 625 square millimeters to be extensivewith the area of substrate 42.

Referring to FIGS. 8-12 the conformableness of template 114 affords mold136 the functionality so that control of thicknesses t₁ and t₂ may beachieved in the face of undulations. Specifically, mold 136 contactsimprinting material so that formation 250 may be formed. Formation 250has a first surface 252 that rests against substrate 42 and has aprofile matching the profile of the surface 44 of substrate 42 in thepresence of undulations. However, a difficulty presented by flexiblemold 236 results from the generation of capillary forces between mold136 and the polymerizable material in droplets 46. Upon contact by mold136 with a first sub-portion of the polymerizable material, e.g.,droplets 46 in region 158, capillary forces between mold 136 and thepolymerizable material are generated. However, capillary forces aresubstantially absent in the remaining sub-section of the polymerizablematerial, e.g., droplets in regions 160 and 161. To form formation 250,fluid pressure is applied to side 115 to deform template 114 and,therefore, mold 136 so that the same contacts droplets 46 in regions 160and 161.

As a result of the flexibility of mold 136, control of thicknesses t₁and t₂, is achieved so that thickness t₁ is within a specified tolerance±δt₁, referred to as being substantially uniform. Similarly thickness t₂is substantially uniform in that the same is within a specifiedtolerance ±δt₂. The tolerance results from the distortion in thefeatures that result from the mold 136 conforming to surface 44. It wasdetermined, however, that by maintaining δt₁ and δt₂ to be less than orequal to 5 nanometers over a 25 millimeter area that the distortionsthat result from the conformableness of mold 136 are acceptable.Specifically, after a break-through-etch of formation 250, regions 162over the entire area of substrate 42 are exposed. Thereafter, patterningof the entire surface of substrate may occur, shown as recessions 164.In this manner, the entire substrate 42 may be patterned, therebyovercoming the problems associated with thickness t₁ having, as well asthickness t₂, varying, over an area of substrate 42 to be patterned.

Referring to both FIGS. 8 and 13, although template 114 is shown havinga mold 136 with protrusions lying in a common plane P along with surface116, other templates may be employed. For example, template 214 mayinclude a mesa 235 that embodies mold 236. Typically, a height, h, ofmesa 235 is approximately 15 micrometers, as measured from surface 216to a top surface of a protrusion 240.

Referring to both FIGS. 8 and 14, in another embodiment, template 314 issubstantially identical to template 114, excepting that mold 336 issurrounded by an entrainment channel 337. Entrainment channel 337extends further from side 316 than recessions 338. In yet anotherembodiment, template 414, shown in FIG. 15, is substantially identicalto template 114, shown in FIG. 8, excepting that regions of side 416lying outside of mold 436 are coplanar with recessions 438.

Referring to FIGS. 4, 13 and 16, during an exemplary operation, template214 and substrate 42 are placed in proximity to one another, e.g.,within one millimeter, at step 500. At step 502, template 214 is bowedso that side 216 facing substrate 42 and, therefore, mold 236, both havea convex shape, defining a bowed template. Specifically, a neutral axis,N, of mold 236 is bowed so that a central portion moves 350-400micrometers away from neutral axis N so as to have a curved shape. Atstep 504, the relative distance between the bowed template and substrate42 is reduced so that the bowed mold 236 is placed in contact with oneor more of droplets 46 of imprinting material and subsequently conformsto the shape of the imprinting material disposed between mold 236 andsubstrate 42 under compression therebetween. Typically, mold 236 iscentered with respect to substrate 42 before contacting the imprintingmaterial. A central portion 233 of mold 236 is centered with respect tothe area of substrate 42 that is to be patterned. In this example,nearly an entire surface 44 of substrate 44 is to be patterned. Thedimension of the area of substrate 42 to be patterned is defined by thethicknesses of formation 250 and the aggregate volume of polymerizablematerial in droplets 46. As a result, the area of mold 236 may begreater, less than or equal to the area of substrate 42. Typically,central portion 233 of mold 236 contacts the center of the area (notshown) with the remaining portions of the imprinting area beingsubsequently contacted by the non-central portions of mold 236.

At step 506, fluid pressure is applied to side 115 to attenuate, if notabrogate, variations among thickness t₁ of the area of formation 150 andvariations among thickness t₂ over the area of formation 150.Specifically, side 115 is subjected to a sufficient magnitude of fluidpressure to compress imprinting material between mold 236 and substrate42 to the state whereby the imprinting material can no longer undergocompression. In this condition, the imprinting material demonstratesvisco-elastic properties in that the same behaves as a solid. Further,in the visco-elastic state the imprinting material conforms fully withsurface 44 so that a side of the imprinting material facing mold 236 hasthe same shape as surface 44. Mold 236 is established to be morecompliant than the imprinting material in a visco-elastic state and,therefore, fully conforms to the shape of the side of the imprintingmaterial facing mold 236. At step 508, imprinting material is exposed toactinic radiation to solidify the same so as to conform to a shape ofthe mold 236 and surface 44 of substrate 42. At step 510, mold 236 isseparated from the solidified imprinting material.

Referring to FIGS. 12, 17 and 18, to facilitate control of the pressureson side 215 of template 214, disposed opposite to mold 236, a chuck body520 is adapted to retain template 214 employing vacuum techniques. Tothat end, chuck body 520 includes first 522 and second 524 opposedsides. A side, or edge, surface 526 extends between first side 520 andsecond side 524. First side 522 includes a first recess 532 and a secondrecess 534, spaced-apart from first recess 532, defining first 536 andsecond 538 spaced-apart support regions. First support region 536cinctures second support region 538 and the first 532 and second 534recesses. Second support region 538 cinctures second recess 534. Aportion 540 of chuck body 520 in superimposition with second recess 534is transmissive to energy having a predetermined wavelength, such as thewavelength of actinic energy employed to solidify the polymerizablematerial mentioned above. To that end, portion 540 is made from a thinlayer of material that is transmissive with respect to broad bandultraviolet energy, e.g., glass. However, the material from whichportion 540 is made may depend upon the wavelength of energy produced bysource 26, shown in FIG. 1.

Referring again to FIGS. 17 and 18, portion 540 extends from second side524 and terminates proximate to second recess 534 and should define anarea at least as large as an area of mold 236 so that mold 236 is insuperimposition therewith. Formed in chuck body 520 are one or morethroughways, shown as 542 and 544. One of the throughways, such asthroughway 542, places first recess 532 in fluid communication with sidesurface 526. The remaining throughways, such as throughway 542, placessecond recess 532 in fluid communication with side surface 526.

It should be understood that throughway 542 may extend between secondside 524 and first recess 532, as well. Similarly, throughway 544 mayextend between second side 524 and second recess 534. What is desired isthat throughways 542 and 544 facilitate placing recesses 532 and 534,respectively, in fluid communication with a pressure control system,such a pump system 546.

Pump system 546 may include one or more pumps to control the pressureproximate to recesses 532 and 534, independently of one another.Specifically, when mounted to chuck body 520, template 136 rests againstfirst 536 and second 538 support regions, covering first 532 and second534 recesses. First recess 532 and a portion 548 of template 136 insuperimposition therewith define a first chamber 550. Second recess 534and a portion 552 of template 136 in superimposition therewith define asecond chamber 554. Pump system 546 operates to control a pressure infirst 550 and second 554 chambers. Specifically, the pressure isestablished in first chamber 550 to maintain the position of thetemplate 214 with the chuck body 520 and reduce, if not avoid,separation of template 214 from chuck body 520 under force of gravity{right arrow over (g)}. The pressure in second chamber 554 may differfrom the pressure in first chamber 548 to reduce, inter alia,distortions in the pattern generated by template 214 during imprinting,by modulating a shape of template 214. For example, pump system 546 mayapply a positive pressure in chamber 554 for the reasons discussedabove. Pump system 546 is operated under control of processor 32, shownin FIG. 1.

Referring to FIGS. 1, 17 and 19, template 214 is coupled to imprint head20 via coupling of chuck body 520 to a flexure 556 that is coupled to anorientation system 558. Orientation system 558 moves template 214.Flexure 556 is disclosed and claimed in U.S. patent application Ser. No.11/142,838, filed Jun. 1, 2005, entitled “Compliant Device forNano-Scale Manufacturing”, which is assigned to the assignee of thepresent invention, and is incorporated by reference herein. Orientationsystem 558 is disclosed in U.S. patent application Ser. No. 11/142,825,filed Jun. 1, 2005 entitled “Method and System to Control Movement of aBody for Nano-Scale Manufacturing,” which is assigned to the assignee ofthe present invention and incorporated by reference herein.

Referring to both FIGS. 19 and 20, orientation system 558 is shownhaving an inner frame 560 disposed proximate to an outer frame 562, andflexure ring 564, discussed more fully below. Body 520 is coupled toorientation system 558 through flexure 556. Specifically, body 520 isconnected to flexure 556, using any suitable means, such as threadedfasteners (not shown) located at the four corners of body 520 connectingto four corners of flexure 556 closest to the four corners of body 520.Four corners 566 of flexure 556 that are closest to a surface 568 ofinner frame 560 are connected thereto using any suitable means, such asthreaded fasteners, not shown.

Inner frame 560 has a central throughway 570, and outer frame 562 has acentral opening 572 in superimposition with central throughway 570.Flexure ring 564 has an annular shape, e.g., circular or elliptical, andis coupled to inner frame 560 and outer frame 562 and lies outside ofboth central throughway 570 and central opening 572. Specifically,flexure ring 564 is coupled to inner frame 560 at regions 574, 576 and578, and outer frame 562 at regions 580, 582 and 584 using any suitablemeans, such as threaded fasteners (not shown). Region 580 is disposedbetween regions 574 and 576 and disposed equidistant therefrom; region582 is disposed between regions 576 and 58 and disposed equidistanttherefrom; and region 584 is disposed between regions 574 and 58 anddisposed equidistant therefrom. In this manner, flexure ring 564surrounds flexure 556, body 520, and template 214 and fixedly attachesinner frame 560 to outer frame 562.

It should be understood that the components of orientation system 558and flexure 556 may be formed from any suitable material, e.g.,aluminum, stainless steel and the like. Additionally, flexure 556 may becoupled to orientation system 558 using any suitable means. In thepresent example, flexure 556 is coupled to surface 45 employing threadedfasteners (not shown) located at the four corners 586.

Referring to FIGS. 17 and 19, system 558 is configured to controlmovement of template 214 and to place the same in a desired spatialrelationship with respect to a reference surface, such as substrate 42disposed on stage 11. To that end, a plurality of actuators 588, 590 and592 are connected between outer frame 562 and inner frame 560 so as tobe spaced about orientation system 558. Each of actuators 588, 590 and592 has a first end 594 and a second end 596. First end 594 faces outerframe 562, and second end 596 faces away from outer frame 562.

Referring to both FIGS. 19 and 20, actuators 588, 590 and 592 tilt innerframe 560 with respect to outer frame 562 by facilitating translationalmotion of inner frame 560 along three axes Z₁, Z₂, and Z₃. Orientationsystem 558 may provide a range of motion of approximately ±1.2 mm aboutaxes Z₁, Z₂, and Z₃. In this fashion, actuators 588, 590 and 592 causeinner frame 560 to impart angular motion to both flexure 556 and,therefore, template 214 and body 520, about one or more of a pluralityof axes T₁, T₂ and T₃. Specifically, by decreasing a distance betweeninner frame 560 and outer frame 562 along axes Z₂ and Z₃ and increasinga distance therebetween along axis Z₁, angular motion about tilt axis T₂occurs in a first direction.

Increasing the distance between inner frame 560 and outer frame 562along axes Z₂ and Z₃ and decreasing the distance therebetween along axisZ₁, angular motion about tilt axis T₂ occurs in a second directionopposite to the first direction. In a similar manner angular movementabout axis T₁ may occur by varying the distance between inner frame 560and outer frame 562 by movement of inner frame 560 along axes Z₁ and Z₂in the same direction and magnitude while moving of the inner frame 560along axis Z₃ in a direction opposite and twice to the movement alongaxes Z₁ and Z₂. Similarly, angular movement about axis T₃ may occur byvarying the distance between inner frame 560 and outer frame 562 bymovement of inner frame 560 along axes Z₁ and Z₃ in the same directionand magnitude while moving of inner frame 560 along axis Z₂ in directionopposite and twice to the movement along axes Z₁ and Z₃. Actuators 588,590 and 592 may have a maximum operational force of ±200 N. OrientationSystem 558 may provide a range of motion of approximately ±0.15° aboutaxes T₁, T₂, and T₃.

Actuators 588, 590 and 592 are selected to minimize mechanical partsand, therefore, minimize uneven mechanical compliance, as well asfriction, which may cause particulates. Examples of actuators 588, 590and 592 include voice coil actuators, piezo actuators, and linearactuators. An exemplary embodiment for actuators 588, 590 and 592 isavailable from BEI Technologies of Sylmar, Calif. under the trade nameLA24-20-000A and are coupled to inner frame 560 using any suitablemeans, e.g., threaded fasteners. Additionally, actuators 588, 590 and592 are coupled between inner frame 560 and outer frame 562 so as to besymmetrically disposed thereabout and lie outside of central throughway570 and central opening 572. With this configuration an unobstructedthroughway between outer frame 562 to flexure 556 is configured.Additionally, the symmetrical arrangement minimizes dynamic vibrationand uneven thermal drift, thereby providing fine-motion correction ofinner frame 560.

The combination of the inner frame 560, outer frame 562, flexure ring564 and actuators 588, 590 and 592 provides angular motion of flexure556 and, therefore, body 520 and template 214 about tilt axes T₁, T₂ andT₃. It is desired, however, that translational motion be imparted totemplate 214 along axes that lie in a plane extending transversely, ifnot orthogonally, to axes Z₁, Z₂, and Z₃. This is achieved by providingflexure 556 with the functionality to impart angular motion upontemplate 214 about one or more of a plurality of compliance axes, shownas C1 and C2, which are spaced—part from tilt axes T₁, T₂ and T₃ andexist on the surface of the template when the template, the templatechuck, and the compliant device are assembled.

Another embodiment of the present invention facilitates separation ofmold 236 from the solidified imprinting material which forms, forexample, formation 50. This is based upon the finding that localizinginitial separation to a relatively small area of the interface betweenmold 236 and the solidified imprinting material reduces the magnitude ofupwardly forces imparted upon mold 236 by orientation system 558necessary to achieve separation. A desirable result is that theprobability of separation between substrate 42 and stage 11 is reduced.

Referring to FIG. 21, a deleterious situation that the present inventionseeks to avoid separation of substrate 42 from stage 11 upon separationof mold 236 from formation 50. Imprint head 20 applies a sufficientforce to overcome the forces of attraction between mold 236 andformation 50. In the situation in which the area of mold 236 issubstantially co-extensive with the area of substrate 42, e.g., wholewafer imprinting, the force required to separate mold 236 from formation50 is often much greater than the force of attraction between substrate42 and stage 11, e.g., a vacuum or electrostatic force of attractionbetween substrate 42 and stage 11. Therefore, it is desirable to reducethe force applied to template 214 necessary to achieve separation ofmold 236 from formation 50. Specifically, it is desirable to ensure thatthe upwardly force required to separate template 114 from formation 50is less than the downwardly applied by stage 11 to substrate 42 tomaintain the same thereupon.

The upwardly force required to separate template 214 from formation 50is reduced by creating localized separation between mold 236 andformation 50 at a region proximate to a periphery of mold 236. To thatend, for mold 236 having an area substantially coextensive withsubstrate 42, mold 236 will have a maximum area to ensure that aperimeter 237 thereof is spaced-apart from an edge 222 of substrate 42approximately 1 millimeter, shown as distance R. Localized separation isobtained by initiating separation of mold 236 from the solidifiedimprinting material employing pump system 546 pressurizing chamber 554to approximately 20 kPa. This distorts the shape of a region 217 oftemplate 214 that surrounds mold 236. A first portion 219 of the surfacetemplate 214 in region 217 is displaced downwardly away from a neutralposition N_(p) toward substrate 42, with the nadir of portion 219 beingapproximately 1 micrometer below surface 43 of substrate 42. As aresult, the distortion afforded to template 214 by pump system 546should be sufficient to allow nadir portion 219 to extend from theneutral position N_(P) a magnitude that is greater than the thicknesst₁, shown in FIG. 3, and height h, shown in FIG. 13.

Referring again to FIGS. 21 and 22, a second portion 220 of the surfaceof template 214 moves upwardly away from substrate 42, with an apexthereof being spaced-apart from surface 43 approximately fifteenmicrometers. A segment of template disposed between second portion 220and nadir portion 219 contacts edge 222 of substrate 42. The Young'smodulus associated with template 214 results in a returning force F_(R)to facilitate returning region 217 to neutral position N_(P), whereinundulations shown as nadir portion 219 and second portion are attenuatedto form arcuate surface 224. The returning force F_(R) results from thematerial of template 214 undergoing movement to return to areduced-stressed and/or reduced-strained state.

Referring to both FIGS. 21, 24 and 25, the returning force F_(R) causesan area 221 of mold 236 proximate to region 217 to separate fromsubstrate 42, while segment 227 functions to press substrate 42downwardly against stage 11, firmly securing the same together. In thismanner, separation mold 236 from formation 50 occurs by cantileveringtemplate 214 with respect to substrate 42. Specifically, portion 227contacts edge 222 of substrate 42 holding the same against stage 11,which reduces the upwardly force on template 214 required to separatemold 236 from substrate and prevents substrate 42 from separating fromstage 11. It can be said, therefore, that returning force F_(R) reducesthe magnitude of the upwardly forces imparted upon mold 236 byorientation system 558 that are necessary to achieve separation. As aresult, returning force F_(R) must be greater than the adhering forcebetween area 221 and formation 50. The returning force F_(R) results inan oblique angle θ being formed with respect to formation 50, measuredfor example, between a plane P₂ in which nadir surfaces 138 ofrecessions 38 lie and a plane P₃ in which nadir surfaces 154 of recessedregions 54 lie. The back pressure and returning force F_(R) coupled withthe angle θ, causes template 214 and, therefore, mold 236, to have anarcuate shape in which region 221 is further from formation 50 thanregions of mold 236 disposed remotely therefrom, center portions of mold236 located proximate to center axis A. Typically, the angle θ will beon the order of micro-radians so that shearing of features in solidifiedlayer 50 is on the order of pico-meters. The remaining portions of mold236 are separated from formation 50 may be controlled by operation ofactuators 588, 590 and 592, shown in FIG. 19.

Referring to both FIGS. 19 and 25, by having actuators 588, 590 and 592move at approximately the same rate, mold 236 is separated fromformation so that the last portions thereof proximate to region 221 areseparated from formation 50 before regions proximate to center axis A.In this manner, regions of mold 236 that are radially symmetricallydisposed about axis A are sequentially separated from formation 50,e.g., region 221 separates then region 223, then region 225 and etc. Itshould be understood, however, that regions 221, 223 and 225 areradially symmetrically disposed about axis A, due to the shape of mold236. It is entirely possible that mold 236 have a rectangular or squareshape. As a result, the shape of regions sequentially removed fromformation 50 would be complementary to the shape of perimeter 237. As aresult, regions of mold 236 that are concentric with respect toperimeter 237 are sequentially separated from formation 50. It should beunderstood, however, that actuators 588, 590 and 592 may be operated soas to produce a peeling separation of mold 236 from formation 50. Thismay be achieved by moving mold 236 about on of tilt axes T₁, T₂ and T₃.

Referring to FIGS. 21 and 22, another manner to achieve localizedseparation of template 214 would include forming arcuate surface 224 oftemplate that is proximate to mold 236. Specifically, pump system 546would create a pressure in pressurizing chamber 554 sufficient to bowarcuate surface 224 and provide the same with a substantially constantradius of curvature. The returning force F_(R) would induce localizedseparation between mold 236 and formation 50 proximate to region 221, asdiscussed above. Thereafter, mold 236 may be separated from formation 50employing the techniques discussed above. Forming contoured surface isparticularly advantageous were mold 236 sized so as to be much smallerthan the area of substrate 42, e.g., were mold 236 to have an area of625 square millimeters, cantilevering would not occur.

The embodiments of the present invention described above are exemplary.Many changes and modifications may be made to the disclosure recitedabove, while remaining within the scope of the invention. The scope ofthe invention should not, therefore, be limited by the abovedescription, but instead should be determined with reference to theappended claims along with their full scope of equivalents.

1. A method for spreading a conformable material between a substrate andan imprint template having a mold, said method comprising: positioningsaid mold to be in superimposition with said substrate defining a volumetherebetween, said substrate having a non-planar surface; charging afirst sub-portion of said volume with said conformable material throughcapillary action between said conformable material and one of said moldand said substrate; deforming said mold to conform to said non-planarsurface to fill a second sub-portion of said volume; and, solidifyingsaid conformable material, said solidified conformable material having aresidual layer with substantially uniform thickness.
 2. The method asrecited in claim 1 wherein said template includes a first side, disposedopposite to said mold, with filling further including creating apressure differential, such that a quantitative difference in pressureexists between said first side of said template as compared to a surfaceof said mold.
 3. The method as recited in claim 1 wherein said moldincludes a central portion and filling further includes contactingconformable material with said central portion and subsequentlycontacting the remaining portions of said mold with said conformablematerial.
 4. The method as recited in claim 1 wherein said mold includesa neutral axis and charging further includes bowing said neutral axisbefore contacting said conformable material.
 5. The method as recited inclaim 1 wherein positioning further including centering said mold withrespect to said substrate.
 6. The method as recited in claim 1 whereinsaid mold has an area associated therewith that is greater than an areaof said substrate.
 7. The method as recited in claim 1 wherein saidtemplate includes a first side, disposed opposite to said mold, withcharging said first sub-portion of said volume with said conformablematerial further including varying a distance between said mold and saidsubstrate, while maintaining a substantially equal pressure on saidfirst side and said mold.
 8. A method for spreading a conformablematerial between a non-planar substrate and a template having a mold,said method comprising: positioning said mold to be in superimpositionwith said substrate defining a volume therebetween; charging a firstsub-portion of said volume with said conformable material throughcapillary action between said conformable material and one of said moldand said substrate; and, filling a second sub-portion of said volume bycreating a deformation in said mold wherein charging occurs beforefilling.
 9. The method as recited in claim 1 wherein said firstsub-portion has a first volume and said second sub-portion has a secondvolume wherein said first volume and said second volume collectively areless than said volume defined by said mold in superimposition with saidsubstrate.
 10. A method for spreading a conformable material between asubstrate and a template having a mold and a first side disposedopposite to said mold, said substrate having a non-planar surface, saidmethod comprising: positioning said mold to be in superimposition withsaid substrate defining a volume therebetween, with said mold having acentral portion; charging a first sub-portion of said volume with saidconformable material through capillary action between said conformablematerial and one of said mold and said substrate by contacting saidconformable material with said central portion; and filling a secondsub-portion of said volume by conforming said mold to said non-planarsurface of said substrate by creating a pressure differential, such thata quantitative difference in pressure exists between said first side ofsaid template as compared to a surface of said mold.
 11. A method forspreading a conformable material between a non-planar substrate and atemplate having a mold, said method comprising: positioning said mold tobe in superimposition with said substrate defining a volumetherebetween, with said mold having a central portion; charging a firstsub-portion of said volume with said conformable material throughcapillary action between said conformable material and one of said moldand said substrate by contacting said conformable material with saidcentral portion; and filling a second sub-portion of said volume bycreating a deformation in said mold by creating a pressure differential,such that a quantitative difference in pressure exists between saidfirst side of said template as compared to a surface of said mold;wherein said mold includes a neutral axis and charging further includesbowing said neutral axis before contacting said conformable material.12. The method as recited in claim 10 wherein positioning said mold tobe in superimposition with said substrate further includes centeringsaid mold with respect to said substrate.
 13. The method as recited inclaim 10 wherein charging the first sub-portion of said volume with saidconformable material further includes varying a distance between saidmold and said substrate, while maintaining a substantially equalpressure on said first side and said mold.
 14. The method as recited inclaim 10 wherein said first sub-portion has a first volume and saidsecond sub-portion has a second volume wherein said first volume andsaid second volume collectively are less than said volume defined bysaid mold in superimposition with said substrate.
 15. The method asrecited in claim 1 wherein charging said first sub-portion of saidvolume with said conformable material occurs before deforming said moldto fill said second sub-portion of said volume.
 16. A method forspreading conformable material over a substrate employing a templatehaving a mold, said substrate having a non-planar surface with at leastone hill and at least one trough, said method comprising: placing saidmold in superimposition with said conformable material; generatingcapillary forces between said mold and a first portion of saidconformable material, said first portion of said conformable materiallocated on said hill of said non-planar surface with capillary forcesbeing substantially absent between in the remaining portions of saidconformable material and said mold; and creating additional capillaryforces between said mold and said remaining portions of said conformablematerial by deforming said mold to conform to said non-planar surface,whereby an imprinting layer having desired thicknesses is formed in saidimprinting area.
 17. The method as recited in claim 16 wherein saidthicknesses include a height thickness and a residual thickness thatdiffers from said height thickness.
 18. The method as recited in claim16 wherein said template includes a first side, disposed opposite tosaid mold, with creating additional capillary forces between said moldand said remaining portions of said conformable material furtherincluding forming a pressure differential, such that a quantitativedifference in pressure exists between said first side of said templateas compared to a surface of said mold.
 19. The method as recited inclaim 16 wherein said mold includes a central portion and generatingcapillary forces between said mold and a first portion of saidconformable material further includes contacting said imprinting areawith said central portion and subsequently contacting the remainingportions of said mold with said imprinting area.
 20. The method asrecited in claim 16 wherein said mold includes a neutral axis andgenerating capillary forces between said mold and a first portion ofsaid conformable material further includes bowing said neutral axis andcontacting said imprinting area after bowing said neutral axis.
 21. Themethod as recited in claim 16 wherein placing said mold insuperimposition with said conformable material further includingcentering said mold with respect to said substrate.